1. Field of the Invention
At least one embodiment of the present invention is directed to the field of stents and stent delivery systems used to treat stenoses, and more particularly to stenoses at a bifurcation of a passage.
2. Description of the Related Art
Stent systems are widely used in the treatment of stenoses. Intravascular stents are used in coronary, renal, and carotid arteries, for example, to maintain an open passage through the artery. In patients whose coronary heart disease consists of focal lesions, stents have proven effective. For example, where only a single coronary artery is clogged or where there are short blockages in more than a single artery, stents have been used with a great amount of success. An intravascular stent may be positioned in a clogged artery by a catheter and is often set in place by inflating a balloon upon which the stent is mounted. This expands the diameter of the stent and opens the previously clogged artery. The balloon is then deflated and removed from the patient while the stent retains an open passage through the artery.
It is recognized, however, that a stent can be deployed in manners other than inflating and deflating a balloon. For example, self-expanding stents have been developed in which a cover is removed from over a stent, thereby allowing the stent to deploy or spring into place. It is also contemplated that other deployment mechanisms or means may be used or developed to advantageously deliver and deploy a stent in position.
Nevertheless, a need still exists for properly delivering and locating a stent at a bifurcation. Although efforts have been made to use a stent at bifurcations, these sites have previously been inadequately treated by a stent. For example, U.S. Pat. No. 5,749,825 is representative of a catheter system that treats stenoses at an arterial bifurcation. The disclosure of U.S. Pat. No. 5,749,825 is hereby incorporated by reference.
A stent having different diameters has been proposed to allow placement in both a main passage, such as an artery, and a side branch passage, such as a continuation branch artery. Additionally, these stents generally have a circular opening which allows for unimpeded blood flow into the side branch artery. However, problems are still encountered in orienting the stent relative to the side branch at the bifurcation of the main and branch passages.
Many current devices rely on either passive torque (e.g., pushing the stent forward and allowing the stent that is fixed on the guide wire/balloon to passively rotate itself into place) or creating torque from outside of the patient to properly orient the stent delivery system in the passage. These devices and methods of achieving proper angular orientation have not been shown to be effective in properly placing and positioning the stent. As will be appreciated and understood by those skilled in the art, improper placement of the stent with respect to its rotational or circumferential orientation, or its longitudinal placement, could lead to obstruction of the side branch passage. It is important to properly position or center an opening formed in the bifurcated stent with the side branch passage to maximize flow therethrough.
Thus, a need exists for effectively treating stenosed passage bifurcations. This need includes more precise and exact longitudinal placement and rotational/circumferential orientation of the stent.
Commercially available devices do not maintain side branch access at the time of stent deployment. This results in the potential for plaque shift and occlusion of the side branch passage.
It would also be advantageous if stents could be placed across the side branch while wire position is maintained thereby helping to protect and secure further access to the side branch.
All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims.